1. Field of the Invention
The present invention relates to an image display device, and in particular, to an image display device having a function of expanding and displaying part of an image.
2. Description of Related Art
There has been hitherto provided a digital broadcast receiver with a function of displaying a slave screen in part of a display screen and of independently displaying images on the slave screen and a master screen in an area except the slave screen respectively, that is to say, with a Picture-In-Picture function (hereinafter referred to as “PinP function”).
Using the PinP function enables different images to be displayed on one screen by displaying, for example, an image of a program broadcasted from one television broadcasting station on a master screen and an image of a program broadcasted from the other television broadcasting station on a slave screen at the same time. Specifically, displaying a television drama on the master screen and a relay of a baseball game on the slave screen allows a viewer to simultaneously watch two different broadcast programs, for instance, to watch mainly a drama while confirming the progress of baseball game.
However, as described above, the PinP function is a function to display two different received images on one screen at the same time, so that the function has such a problem that part of one received image displayed on the master screen cannot be expanded and displayed on the slave screen.
Japanese Patent Laid-Open No. 2002-142171, for example, proposes an image display device, as a device for solving this problem, in which an arbitrary partial area is segmented from one received image displayed on the master screen (hereinafter referred to as “original image”), enlarged, synthesized with the original image and displayed on one screen. According to the proposal described in Japanese Patent Laid-Open No. 2002-142171, since an original image can be displayed on the master screen and an arbitrary partial area of the original image can be expanded and displayed on the slave screen, for example, when a viewer desires to confirm expanded scores and counts displayed at the lower corners of a screen while watching a relay of a baseball game, a relay of a baseball game can be displayed on the master screen and scores and counts can be expanded and displayed on the slave screen.
According to the proposal described in Japanese Patent Laid-Open No. 2002-142171, however, the slave screen is stationarily arranged at a location where the slave screen is superimposed on the expanded area in the original image displayed on the master screen, so that the part where the viewer wants to watch sometimes cannot be watched. Although the device is configured so that an expanded area is set and a slave screen can be displayed by the viewer operating a remote controller, once the expanded area and slave screen are set, their contents are held as long as the viewer does not change the set contents, so that the viewer has to set the change of the expanded area and the termination of expansion display in each case, which is time-consuming and is not user friendly.